Concrete crushing grappler

ABSTRACT

The pliers have hinged jaws (1,2) moved using hydraulic cylinders. The first jaw has a frame body (6) with first breaking and cutting areas. The second jaw has a body (7) with second breaking and cutting areas. When the pliers are closed, the second jaw fits in the first jaw and the breaking and cutting areas co-operate. The cutting areas have cutting elements (17,20), which are releasably fixed in holder pockets in the jaws.

FIELD OF THE INVENTION

The present invention relates to concrete-crushing pincers.

Concrete-crushing pincers are utilized for demolishing structures madeof reinforced concrete. In this connection, it is particularly desirablethat through the pincer movement of the concrete-crushing pincers, theconcrete is crushed, on the one hand, and the reinforcing iron is cut inthe same course of movement, on the other hand. The demolition materialthus broken up can thereby be fed for further processing to, forexample, a breaker in which separation of concrete and metal takesplace, without any additional working operation, such as severingreinforcing iron with a cutting torch if it is not optimally cut by theconcrete-crushing pincers.

Such concrete-crushing pincers are known. Thus, for example, suchconcrete-crushing pincers are shown in U.S. Pat. No. 5,183,216. Theseconcrete-crushing pincers also comprise, besides the crushing teeth,cutting elements which are held in rectangular-shaped recesses. Duringcutting of the reinforcing irons, these cutting elements are subjectedto high stresses. Areas of the rectangular-shaped recesses may therebybe excessively stressed, which may result in deformation. This leads todamage of the recesses, which must be eliminated by expensive repairwork.

In European Patent No. 0 770 164, concrete-crushing pincers are shownwhich have two pincer jaws, each of which is provided withconcrete-crushing sectors and cutting edges. The concrete-crushingsectors project over the cutting edges, to avoid crushing of theconcrete by the cutting edges which are provided for cutting thereinforcing iron and should therefore have a relatively sharp edge. Theconcrete-crushing edge and the cutting edge are rotary, i.e., in orderto be able to cut the reinforcing iron optimally, the concrete-crushingedge must not project too far over the cutting edge. The cutting edge isalso highly stressed by the crushing of the concrete, which may resultin heavy wear and tear and expresses itself in decreasing cuttingquality for the reinforcing iron.

Since the cutting edges are exposed to high forces of traction andcompression during cutting of the reinforcing iron, the respectivecutting elements must be optimally joined to the respective pincer jaw.In these previously described concrete-crushing pincers, this isachieved in that the material forming the cutting edge is welded ontothe pincer jaw. This has the drawback, however, that in case of wear ofthis cutting edge, new material must be welded on, which usually takesplace in a workshop, whereby the pincers are not in operation for sometime, and long down-times occur. Furthermore, additional material cannotbe welded onto the pincer jaw as often as desired since structuralmodifications of the material occur through the heating, whereby thestrength of this material and hence the connection between welded-onmaterial and pincer jaw is no longer optimal and the additional materialmay break off.

SUMMARY OF THE INVENTION

A task of the present invention now consists in creatingconcrete-crushing pincers in which the renewal of the cutting edges maybe carried out without requiring long stoppage times, and in whichoptimum crushing of the concrete is achieved.

According to the invention, the solution of this task takes place bymeans of the following features. Concrete-crushing pincers having afirst pincer jaw and a second pincer jaw are connected to one anothervia a joint and are movable via hydraulic cylinders about a swivel axisformed by the joint from an open position into a closed position. Thefirst pincer jaw is formed by a frame body in which firstconcrete-crushing sectors and first cutting sectors are disposed. Thesecond pincer jaw is formed by a body on which second concrete-crushingsectors and second cutting sectors are disposed, which, during closingof the concrete-crushing pincers, while the second pincer jaw penetratesinto the frame body of the first pincer jaw, cooperate with the firstconcrete-crushing sectors and the first cutting sectors of the firstpincer jaw. The first and the second cutting sectors are each formed offirst and second cutting elements, respectively, which are inserted inreceiving pockets affixed in the first pincer jaw and the second pincerjaw and are detachably fastened therein, such that the first cuttingelements are fastened to the lateral areas of the first pincer jaw andthe second pincer jaw. The first cutting elements are each formed of ablock provided with a bend, the convex surface of which rests in thereceiving pocket provided with a corresponding support surface, and theconcave surface of which, with the lateral surfaces lying in a planestanding perpendicular to the swivel axis, each form a cutting edge.

By allowing the cutting elements of the concrete-crushing pincers to beexchanged, which can practically be undertaken at the place of use ofthese concrete-crushing pincers, long stoppage times are avoided.

In this connection, first cutting elements, each formed of a blockprovided with a bend, are fastened to the lateral areas of the firstpincer jaw and of the second pincer jaw. Moreover, their convex surfacerests in the receiving pocket of the pincer jaw provided with acorresponding support surface, whereas their concave surfaces each forma cutting edge with the lateral surfaces lying in a plane standingperpendicular to the swivel axis. Besides the advantage that theseindividual blocks can be very quickly replaced, it is thereby alsoachieved that the absorption of the forces during cutting of thereinforcing iron and their transmission to the pincer jaws can takeplace in an optimal manner.

A further advantageous arrangement of the invention includes a guide ribthat is affixed to the convex surface of the previously described block,which guide rib is aligned longitudinally to the convex surface and runscentrally, the respective support surface of the receiving pocket beingequipped with a groove corresponding to the guide rib, in which groovethe guide rib engages when the block is inserted in the pincer jaw. Bymeans of this device, the block is held optimally in the receivingpocket of the respective pincer jaw.

A further advantageous arrangement of the invention includes elementsthat are affixed to the end regions of the support surfaces of thereceiving pockets, which elements are provided with stop surfacesagainst which the end faces of the blocks rest when inserted in thereceiving pockets. By this means, these blocks are optimally held in thereceiving pockets. Since the blocks themselves are not connected to thepincer jaw, for instance with screws, no excessive stress peaks arisethrough the forces occurring during the cutting operation, which stresspeaks might for instance lead to breaking of the screws, since theforces can be optimally led over into the pincer jaw.

Advantageously, first cutting elements formed by the blocks areprovided, disposed two at a time in a row on each lateral area of thepincer jaws, which elements are held in the receiving pockets by teethscrewable onto the pincer jaw. The tips of the teeth project over thecutting edges of the cutting elements, whereby the crushing of theconcrete is at least initiated by these teeth, and the cutting edges arethus spared.

A further advantageous arrangement of the invention includes the bend ofthe block forming the cutting elements is arcuate, whereby the bearingsurface is optimal, and the fabrication of the blocks and the receivingpockets is simplified. The concave surface of the blocks situatedbetween the two cutting edges has a curvature, and the wedge angle ofthe cutting edge becomes greater than 90°. During cutting of thereinforcing iron, the latter thus rests first upon the curvature, it ispressed straight before the cutting edges engage, whereby again thecutting edges are protected. Through the symmetrical arrangement ofthese blocks, this block can be rotated in the receiving pocket in sucha way that one of the two cutting edges is in use each time, whereby thematerial is optimally utilized.

A further advantageous arrangement of the invention includes a plateforming the second cutting element that is affixed to the end-face areaof the first and the second pincer jaw, respectively, which plate restswith one lateral area each on a corresponding support surface of thereceiving pocket, and optimum transmission of force to the pincer jaw isthus achieved.

The rear side of this plate is supported against a wall, adjoining thesupport surface, of the first pincer jaw and the second pincer jaw,respectively, and is screwed to the latter. Thus this plate is alsoeasily exchangeable.

Advantageously, the two lateral surfaces of the plate are provided withindentations and projections, along which the cutting edge runs. Theplate may be inserted in the receiving pocket in such a way that eitherone or the other of the two cutting edges is in use. By this means, too,the material is optimally utilized.

A further advantageous arrangement of the invention includes the platebeing disposed between the two front teeth of the first and/or secondpincer jaw, respectively, with the tips of the teeth projecting over thecutting edge of the plate. The crushing of the concrete is thereby againat least initiated over the teeth, and the cutting edge of the plate isspared as a result.

In order that the concrete may be crushed optimally and the cuttingedges of the cutting elements may be protected, additional teeth areaffixed to the second pincer jaw, and these teeth are disposed betweeneach of two teeth forming a pair and project over their tips. Duringdemolishing of reinforced concrete, the area grasped by the pincers isfirst subjected to bending stress, and the concrete thus breaks moreeasily.

Advantageously, the teeth are disposed in the pincer jaws so that uponclosing of the pincers, first the rear teeth come in contact with theportion of concrete to be broken off, and the concrete is crushed inthis sector, and only thereafter do the front teeth engage. The crushingof the concrete thereby becomes easier.

An embodiment of the present invention is described in detail below, byway of example, with reference to the enclosed drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an embodiment of the concrete-crushing pincers according tothe invention in a perspective view;

FIG. 2 shows a side elevation of the first pincer jaw with the firstcutting elements to be inserted therein and the teeth;

FIG. 3 shows a partial view of the first cutting elements which are in aposition just before the cutting of a reinforcing iron;

FIG. 4 shows a sectional view taken on the line IV—IV through the firstcutting elements according to FIG. 3;

FIG. 5 shows a sectional view corresponding to the sectional viewaccording to FIG. 4, the first cutting elements being in a position ofcutting through the reinforcing iron;

FIG. 6 shows a top plan view of the plates forming the second cuttingelements, which plates are in a position just before cutting through thereinforcing iron;

FIG. 7 shows a sectional view taken on the line VII—VII through thesecond cutting elements depicted in FIG. 6;

FIG. 8 shows a sectional view through the second cutting elementsaccording to FIG. 7, these plates being in a position during cuttingthrough the reinforcing iron;

FIG. 9 shows a diagrammatical view of the opened concrete-crushingpincers which have just engaged a reinforced concrete portion during theclosing operation;

FIG. 10 shows diagrammatically a sectional view taken on the line X—Xaccording to the situation of FIG. 9;

FIG. 11 shows a diagrammatical view of the concrete-crushing pincers,the closing movement of which is advanced as compared with FIG. 9;

FIG. 12 shows a sectional view through the concrete-crushing pincersaccording to FIG. 11 taken on the line XII—XII in a diagrammatical view;

FIG. 13 shows in a diagrammatical view a view of the concrete-crushingpincers, the closing movement of which has been further continued andwhich are in a position shortly before cutting through the reinforcingiron;

FIG. 14 shows a sectional view taken on the line XIV—XIV according toFIG. 13 diagrammatically;

FIG. 15 shows a diagrammatical view of the concrete-crushing pincers ina completely closed state;

FIG. 16 shows a sectional view taken on the line XVI—XVI according toFIG. 15 with severed reinforcing iron; and

FIG. 17 shows a sectional view through the second pincer jaw taken onthe line XVII—XVII according to FIG. 2, with the additional toothdisposed between the rear teeth.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1, the concrete-crushing pincers consist of a firstpincer jaw 1 and a second pincer jaw 2. These first pincer jaw 1 andsecond pincer jaw 2 are connected to one another via a joint 3 and aremovable about a swivel axis 4 formed by the joint 3 from an openposition, as is shown in FIG. 1, into a closed position. This openingand closing of the concrete-crushing pincers takes place in a knownmanner by means of hydraulic cylinders 5, which are showndiagrammatically by way of example in FIG. 9. These concrete-crushingpincers may be fastened in the usual manner to a construction machine,and may be brought into any desired position thereby, while thehydraulic cylinders 5 are controllable via a hydraulic unit provided inthese construction machines.

The first pincer jaw 1 of these concrete-crushing pincers is formed by aframe body 6 which has a free passage on the inside. The second pincerjaw 2 is formed by a body 7 which, upon closing of the concrete-crushingpincers, can penetrate into the frame body 6 of the first pincer jaw 1.

The first pincer jaw l has first concrete-crushing sectors which eachconsist of a rear tooth 9 and a front tooth 10 affixed to the lateralareas 8 of the first pincer jaw 1. The rear teeth 9 and the front teeth10 of the first pincer jaw 1 are screwed onto a crosspiece 11 affixed tothe outside of frame body 6. The rear teeth 9 and the front teeth 10 maythereby be taken out of the first pincer jaw 1 and reinserted and/orexchanged. Affixed to the lateral areas 12 of the second pincer jaw 2 islikewise a rear tooth 13 and a front tooth 14 each, which serve asconcrete-crushing sectors and which are fastened by screwing to acrosspiece, not shown, which is affixed to the inside of the secondpincer jaw. Centrally between the two front teeth 14 of the secondpincer jaw 2, an additional tooth 15 is affixed. This additional tooth15 projects over the two front teeth, the effect achievable thereby willbe described in detail later. Likewise affixed between the rear teeth 13of this second pincer jaw 2 is an additional tooth 16 which is notvisible in FIG. 1 but can be seen in FIG. 17.

Inserted in each case between the joint area and the rear tooth 9, aswell as between the rear tooth 9 and the front tooth 10 of the firstpincer jaw 1, are first cutting elements 17 formed of an arcuate block18. This arcuate block 18 and its fastening in the first pincer jaw 1and the second pincer jaw 2 will be described in detail later.

Fastened to the end-face area 19 of the first pincer jaw 1 and thesecond pincer jaw 2 are second cutting elements 20 which are formed of aplate 21. These plates 21 will also be described in detail later.

As may be seen from FIG. 2, in which the second pincer jaw 2 is shown,the first cutting elements 17 each consist of an arcuate block 18. Thefirst pincer jaw 1 is formed correspondingly. This block 18 has a convexsurface 22 and may be inserted in receiving pockets 23 of the firstpincer jaw 1 and/or the second pincer jaw 2 in such a way that theconvex surface 22 rests on a corresponding support surface 24 of thereceiving pocket 23. The blocks 18 are each held in the receivingpockets 23 at their end faces 25 which rest against stop surfaces 26.These stop surfaces 26 are formed on the one hand by the rear and frontteeth 9 and 10 of the first pincer jaw 1 and 14 and 15 of the secondpincer jaw 2, while the stop surface 26 situated in the region of thejoint 3 is formed integral with the first pincer jaw 1 and the secondpincer jaw 2.

Advantageously, spring elements, not shown, for instance plate springs,may be inserted between the end faces 25 of the blocks 18 and the stopsurfaces 26, which springs might be placed in corresponding recesses.The blocks would thereby be held biased in the receiving pockets 23,allowing the seat between the convex surfaces 22 of the blocks 18 andthe support surfaces 24 to be optimal, even in the case of a possiblyoccurring elastic deformation of the first pincer jaw 1 and/or thesecond pincer jaw 2, so that no soiling of the seat could take place.

As may be seen from FIG. 2, the blocks 18 forming the first cuttingelements 17 may easily be inserted in the pincer jaw 1 or pincer jaw 2and fastened by screwing the rear teeth 9, 13 and/or front teeth 10, 14tightly to the respective pincer jaw 1 or 2. Replacement of these blocks18 may thus be carried out very quickly, for this purpose even only therear tooth 9 or 13 need be taken out in each case. The blocks 18 of thefirst pincer jaw 1 and of the second pincer jaw 2 are identical. Thus,they may be exchanged with each other at will. A mix-up during insertionof the blocks 18 in the pincer jaws 1 and/or 2 is thereby out of thequestion, and differing wear and tear can be offset by mutual exchange.

The cutting operation with these first cutting elements 17, which areformed by the blocks 18, is shown in FIGS. 3 to 5. Upon closing of theconcrete-crushing pincers, the reinforcing iron 27 comes into the regionof the concave surfaces 28 of the blocks 18, as will be seen later. Theconcave surface 28 and the lateral surfaces 29 of the blocks 18 eachform a cutting edge 30. The blocks 18 may thus be inserted in thecorresponding pincer jaws 1 and/or 2 in such a way that one or the othercutting edge 30 is being used for cutting the reinforcing iron. Theconcave surface 28 is furnished with a curvature 31, whereby a wedgeangle β greater than 90°, preferably about 105°, is produced.

Upon closing of the concrete-crushing pincers, the reinforcing iron 27first rests upon the curvatures of the co-operating blocks 18, as isseen in FIG. 4. The reinforcing iron 27 is thereby held fast before thecutting edges 30 begin their cutting operation. During the furtherclosing of the concrete-crushing pincers, pulling of the reinforcingiron 27 into the cutting gap is avoided. The forces acting upon theblocks 18 thereby become more favorable. The cutting operation as shownin FIG. 5 takes place optimally since the reinforcing iron 27 to be cutdoes not have a tendency to become squeezed in the cutting gap, wherebythe latter would in turn have a tendency to become expanded. The cuttingedges 30 are thereby optimally stressed, and the life of the firstcutting elements 17 is extended.

As may be seen particularly from FIGS. 4 and 5, each block 18 isprovided in the region of the convex surface 22 with a guide rib 32which engages a groove 33 that is formed in the respective receivingpocket of the first pincer jaw 1 and the second pincer jaw 2. Optimumholding of the blocks 18 in the respective receiving pockets of thefirst pincer jaw 1 and the second pincer jaw 2 is thereby obtained.

As may be seen from FIGS. 6 to 8, the second cutting elements 20 eachconsists of a plate 21. The particular surface 34 directed toward thecutting plane has a curvature, so that every point of this surface 34 isat the same distance from the swivel axis 4 of the concrete-crushingpincers. The opposing lateral surfaces 35, adjoining this surface 34provided with a curvature, each form together with this surface 34 acutting edge 36. One each of the lateral surfaces 35, when inserted inthe pincer jaws 1, 2, is supported by a support surface 37 which formsthe receiving pocket in the end-face area of the concrete-crushingpincers. The surface of the plate 21 opposite the curved surface 34rests against a wall 38 of the first pincer jaw 1 and/or the secondpincer jaw 2 adjacent to the support surface 37 and is screwed to thisjaw. Thus, these plates 21 forming the second cutting elements 20 mayalso be exchanged in a simple manner. Since the plates 21 are formedsymmetrically, they may also be rotated so that one or the other of thecutting edges 36 is in use.

As may be seen particularly from FIG. 6, the lateral surfaces 35 haveindentations 39 and projections 40. Upon closing of theconcrete-crushing pincers, the reinforcing irons 27 are pushed into theindentations 39 and then clamped fast by the lateral surfaces 35, as isseen in FIG. 7. Upon further closing, the reinforcing irons 27 are cutby the cutting edges 36, with forces acting upon the plates 21 which tryto pull the plates together. With this arrangement, too, the cutting gapis thereby not expanded, but the opposite happens, whereby an optimumcutting effect is achieved. Here, too, the edge angle of the cuttingedge is greater than 900, preferably about 1050, whereby, as mentioned,the cutting edges are protected.

It may be seen from FIG. 17 how the additional tooth 16 in the secondpincer jaw 2 is disposed. Affixed about centrally between the two rearteeth 13 in the second pincer jaw 2 is a plate 42 to which theadditional tooth 16 is affixed. As already seen in FIG. 1, theadditional tooth 15 is also affixed to this plate 42. The additionaltooth 16, as may be gathered from FIG. 17, projects over the two rearteeth 13 of the second pincer jaw 2. The additional tooth 15 alsoprojects, as is seen in FIG. 1, over the two front teeth 14 of thesecond pincer jaw 2. The function of these additional teeth 15 and 16 ofthe second pincer jaw 2 projecting over the two front teeth 14 and/orover the rear teeth 13 will be described in detail below in connectionwith the teeth 9 and 10 of the first pincer jaw 1.

With reference to FIGS. 9 to 16, the mode of operation and function ofthe concrete-crushing pincers according to the invention will bedescribed below. The concrete-crushing pincers, with opened first pincerjaw 1 and second pincer jaw 2, are placed, for example, over a concreteslab 41 reinforced with reinforcing iron 27, as may be seen in FIG. 9.The first pincer jaw 1 and the second pincer jaw 2 are then slowlyclosed about the joint 3 via the hydraulic cylinder 5. The rear teeth 9of the first pincer jaw 1 come to bear on the concrete slab 41. Theadditional tooth 16, which is situated centrally between the rear teeth13 of the second pincer jaw 2 and projects over the latter, likewisepresses on the concrete slab 41. As is seen from FIG. 10, a bendingeffect is thereby produced on the concrete slab, the concrete begins tobreak under the bending forces occurring, as is shown diagrammaticallyin FIG. 10.

The closing movement of the concrete-crushing pincers is continued, asshown in FIGS. 11 and 12. The concrete situated in the region of therear teeth 9 and 13 of the first pincer jaw 1 and the second pincer jaw2 is further crushed, the front teeth 10 of the first pincer jaw arepressed against the concrete slab 41, the additional tooth 15 of thesecond pincer jaw 2, which is situated between the front teeth 14 andlikewise projects over the latter, brings about a bending and acorresponding crushing for this area of the concrete slab 41, too, astook place in the area of the rear teeth 9 and 13. The pieces ofconcrete broken out are ejected through the free opening of the firstpincer jaw 1.

The closing movement of the concrete-crushing pincers is continued, asshown in FIGS. 13 and 14. Here, the concrete-crushing operation, whichhas been carried out particularly by the rear teeth 9 and 13, by thefront teeth 10 and 14, and by the additional teeth 15 and 16 of thefirst pincer jaw 1 and the second pincer jaw 2, is nearly concluded. Thefirst cutting elements 17 and the second cutting elements 20 are onlyslightly involved in the concrete-crushing operation and are thusspared. The wedge shape of the teeth now causes the reinforcing iron tobe pressed into the region of the first cutting elements 17, as is shownin FIG. 13. Upon further closure, the reinforcing irons 27, situated inthe area of the first cutting elements 17, are now cut.

Not until these first cutting elements 17 have cut the reinforcing iron27 situated in their region do the second cutting elements 20 come intouse and cut up the reinforcing irons situated in this region, which runat right angles to those which have been cut by the first cuttingelements 17. This operation takes place in the last part of the closingmovement of the concrete-crushing pincers according to the invention.The projections 40 of the interacting plates 21 cause the reinforcingiron to be cut to be pressed into the indentations 39, where the cuttingtakes place. This state is shown in FIGS. 15 and 16, where the piece ofthe concrete slab 41 grasped by the concrete-crushing pincers is cleanlybroken out, and the reinforcing irons running lengthwise and crosswisehave been cut out. The concrete-crushing pincers may be opened andapplied to another location of the concrete slab 41.

The material of which the blocks 18 and the plates 21 are made consists,for example, of a steel having a hardness of about 58 HRC.

Through the arrangement described previously of the teeth and thecutting elements in the concrete-crushing pincers according to theinvention, first a gradual breaking-out of the concrete is achieved,thereafter the rear part of the reinforcing irons is cut, after whichthe front part of the reinforcing irons is cut, and only then does thesevering of the reinforcing irons situated in the end-face area of theconcrete-crushing pincers take place. By means of this step-by-stepprocedure, optimum effectiveness of the concrete-crushing pincers can beachieved with the closing force usually mustered, the cutting edges forcutting the reinforcing irons being spared and their life thus beingextended. Through the possibility of replacing the cutting elements, theconcrete-crushing pincers can, when these cutting elements show too muchwear and tear, be optimally equipped again in a short time, thisreplacement being able to take place practically at the place of use ofthese concrete-crushing pincers.

What is claimed is:
 1. Concrete-crushing pincers comprising a firstpincer jaw and a second pincer jaw which are connected to one anothervia a joint and are movable via hydraulic cylinders about a swivel axisformed by the joint from an open position into a closed position,wherein the first pincer jaw is formed by a frame body in which firstconcrete-crushing sectors and first cutting sectors are disposed, andwherein the second pincer jaw is formed by a body on which secondconcrete-crushing sectors and second cutting sectors are disposed,which, during closing of the concrete-crushing pincers, while the secondpincer jaw penetrates into the frame body of the first pincer jaw,cooperate with the first concrete-crushing sectors and the first cuttingsectors of the first pincer jaw, and the first and the second cuttingsectors are formed of first and second cutting elements, respectively,which are inserted in receiving pockets respectively affixed in thefirst pincer jaw and the second pincer jaw and are detachably fastenedtherein, wherein: the first cutting elements are fastened to the lateralareas of the first pincer jaw and the second pincer jaw; and the firstcutting elements are each formed of a block provided with a bend, theconvex surface of which rests in the receiving pocket provided with acorresponding support surface, and the concave surface of which, withthe lateral surfaces lying in a plane standing perpendicular to theswivel axis, each form a cutting edge.
 2. The concrete-crushing pincersof claim 1, further comprising: a guide rib affixed to the convexsurface of the first cutting elements that is aligned longitudinally tothe convex surface and runs centrally; wherein: a groove is furnished inthe respective support surface of the receiving pocket corresponding tothe guide rib, in which groove the guide rib engages.
 3. Theconcrete-crushing pincers of claim 1, further comprising elements,provided with stop surfaces, affixed to the end regions of the supportsurfaces of the receiving pockets; wherein: end faces of the blocksforming the first cutting elements rest against the stop surfaces in thestate inserted in the receiving pockets; whereby: the first cuttingelements are held in the receiving pockets.
 4. The concrete-crushingpincers of claim 3, further comprising: first cutting elements disposedtwo at a time in a row on each lateral area of the first pincer jaw andof the second pincer jaw; a rear tooth affixed between the two firstcutting elements on the first pincer jaw and on the second pincer jawforming the rear concrete-crushing sector; a front tooth affixed to theend region facing away from the joint on the first pincer jaw and on thesecond pincer jaw forming the front concrete-crushing sector; wherein:each rear tooth and each front tooth being screwed to the respectivepincer jaw.
 5. The concrete-crushing pincers of claim 4, wherein the tipof each front tooth and of each rear tooth projects over the cuttingedges of the cutting elements.
 6. The concrete-crushing pincers of claim1, wherein the bend of the block forming the first cutting elements isarcuate, such that the concave surface lying between the two cuttingedges has a curvature and the wedge angle is greater than 90°, and thatthe first cutting elements can be so rotated that one of each of the twocutting edges is in use.
 7. The concrete-crushing pincers of claim 1,wherein: the second cutting elements are fastened to the end-face areaof the first pincer jaw and of the second pincer jaw; the second cuttingelements are formed substantially of a plate, the surface of whichdirected toward the cutting plane have a curvature, so that every pointof this surface is at the same distance from the swivel axis; thissurface and the two opposing lateral surfaces adjacent thereto each forma cutting edge; and one of the two lateral surfaces of this plate restson the support surface of the receiving pocket corresponding to thislateral surface.
 8. The concrete-crushing pincers of claim 7, whereinthe surface of the plate opposite the curved surface rests against awall of the first pincer jaw and of the second pincer jaw adjoining thesupport surface and is screwed thereto.
 9. The concrete-crushing pincersof claim 7, wherein the lateral surfaces of the plate are provided withindentations and projections.
 10. The concrete-crushing pincers of claim7, wherein the plate is insertable in the receiving pocket in such a waythat one or the other of the two cutting edges can be utilized forcutting.
 11. The concrete-crushing pincers of claim 7, furthercomprising: first cutting elements disposed two at a time in a row oneach lateral area of the first pincer jaw and of the second pincer jaw;a rear tooth affixed between the two first cutting elements on the firstpincer jaw and on the second pincer jaw forming the rearconcrete-crushing sector; a front tooth affixed to the end region facingaway from the joint on the first pincer jaw and on the second pincer jawforming the front concrete-crushing sector; wherein: the plate isdisposed in each case between the two front teeth of the first pincerjaw and of the second pincer jaw; and the tip of each tooth projectsover the cutting edge of the plate.
 12. The concrete-crushing pincers ofclaim 1, further comprising: at least two teeth disposed on the lateralareas of the first pincer jaw and of the second pincer jaw whichcooperate with one another; and an additional tooth affixed to thesecond pincer jaw about in the middle between each pair of teeth havingsubstantially the same distance from the swivel axis.
 13. Theconcrete-crushing pincers of claim 12, wherein the tip of eachadditional tooth projects over the tips of the two teeth which form thepair of teeth and between which each additional tooth is affixed. 14.The concrete-crushing pincers of claim 11, wherein the tip of each toothwhich is affixed in each case to a lateral area of the first pincer jawand the second pincer jaw, respectively, lie substantially on a straightline which intersects the swivel axis.